ramips: gpio: use module_platform_driver

Use the normal macro to remove some duplication.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/24095
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

target/linux/ramips/files/drivers/gpio/gpio-ralink.c

@@ -308,9 +308,4 @@ static struct platform_driver ralink_gpio_driver = {
 	},
 };
 
-static int __init ralink_gpio_init(void)
-{
-	return platform_driver_register(&ralink_gpio_driver);
-}
-
-subsys_initcall(ralink_gpio_init);
+module_platform_driver(ralink_gpio_driver);